Xref: utzoo comp.sys.amiga.misc:64 comp.sys.amiga.advocacy:57 Path: utzoo!utgpu!news-server.csri.toronto.edu!bonnie.concordia.ca!thunder.mcrcim.mcgill.edu!snorkelwacker.mit.edu!ai-lab!life!burley From: burley@geech.ai.mit.edu (Craig Burley) Newsgroups: comp.sys.amiga.misc,comp.sys.amiga.advocacy Subject: Re: How do we change the scheduler? (Was Re: Multitasking at home...) Message-ID: Date: 14 Jan 91 16:09:25 GMT References: <17210@cbmvax.commodore. <7504@sugar.hackercorp.com> Sender: news@ai.mit.edu Organization: Free Software Foundation 545 Tech Square Cambridge, MA 02139 (617) 253-8568 Lines: 43 In-reply-to: peter@sugar.hackercorp.com's message of 13 Jan 91 00:34:10 GMT Regarding Mac's Multifinder, here is how to tell whether it has true multitasking (which does mean preemptive scheduling in any context I've ever heard the term defined): Start up a comms program and get a reasonably long file transfer going, like via kermit or X-modem. Now switch to the Finder or some other app (perhaps even the comm app itself, though mine, Microphone II, is smart enough to keep things going despite the pulled-down menu -- if it is its own). Now pull down a menu and hold it down for about five minutes. Now go back to the comms program window and see how much stuff has been transferred and whether the transfer has crashed. The answer should be "No, the transfer kept plugging along", but on the Mac it currently is, "Yes, when holding a menu in the pulled-down state, no other tasks on the system continued running except perhaps the vertical retrace task". If the comms program is smart enough to put the file transfer into the vertical retrace task, try using a long compilation instead of a comm program task instead, and see if it keeps compiling even while the menu is held down. Note that in any case, it is absolutely certain that on the current Mac, either you don't have true multitasking and it is fairly easy to expose it, or the programmers of the apps you are using have had to jump through hoops to disguise it (as did the Microphone II engineers -- for which I'm very grateful). (To be fair, as I've posted before, just doing true multitasking requires a bit of jumping through hoops for the OS and its applications -- but nothing like simulating it, efficiently, without actually having it.) Anyone care to post whether this kind of scenario works on the Amiga? I.e. when holding a menu down, or doing other purely user-interface things that aren't inherently resource intensive (like just holding a mouse button down without moving the mouse), does true multitasking keep working? My guess would be yes, it does. -- James Craig Burley, Software Craftsperson burley@ai.mit.edu